How to Install and Use Python on Debian

Python is one of the most popular programming languages in the world. It’s used for web development, data science, machine learning, automation, and more. This guide covers installing and using Python on Debian Linux.

Check Current Python Version

Most Debian versions come with Python pre-installed. Check what’s available:

python3 --version
python --version

which python3
which python

Method 1: Install Python from Debian Repository

Step 1: Update Package Lists

sudo apt update

Step 2: Install Python 3

sudo apt install -y python3

Step 3: Install pip (Package Manager)

pip is Python’s package manager:

sudo apt install -y python3-pip

Step 4: Install Additional Tools

Install common development tools:

sudo apt install -y python3-venv python3-dev build-essential

Method 2: Install Using pyenv (Recommended for Developers)

pyenv allows you to install and manage multiple Python versions:

Step 1: Install Dependencies

sudo apt install -y build-essential libssl-dev zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev curl libncursesw5-dev xz-utils tk-dev libxml2-dev libffi-dev liblzma-dev

Step 2: Install pyenv

curl https://pyenv.run | bash

Step 3: Configure pyenv

Add to your ~/.bashrc:

export PYENV_ROOT="$HOME/.pyenv"
export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init --path)"

Step 4: Install Python Versions

pyenv install 3.12.0
pyenv install 3.11.5
pyenv global 3.12.0

Using Python

Run Python Interpreter

Start interactive Python session:

python3

Example session:

>>> print("Hello, World!")
Hello, World!
>>> 2 + 2
4
>>> exit()

Run a Python Script

Create and run a script:

nano hello.py

#!/usr/bin/env python3
print("Hello, World!")

for i in range(5):
    print(i)

python3 hello.py

Using pip – Package Manager

Install a Package

pip3 install requests

Install Specific Version

pip3 install requests==2.31.0

List Installed Packages

pip3 list

Check for Updates

pip3 list --outdated

Upgrade a Package

pip3 install --upgrade requests

Uninstall a Package

pip3 uninstall requests

Show Package Info

pip3 show requests

Virtual Environments

Virtual environments keep project dependencies separate:

Step 1: Create Virtual Environment

python3 -m venv myenv

Step 2: Activate Virtual Environment

source myenv/bin/activate

Your prompt will change to show the environment name:

(myenv) user@server:~$

Step 3: Install Packages

Now install packages only in this environment:

pip install requests

Step 4: Deactivate

deactivate

Common Python Packages

• requests – HTTP library for web requests
• flask – Lightweight web framework
• django – Full-stack web framework
• numpy – Numerical computing
• pandas – Data analysis
• matplotlib – Data visualization
• scikit-learn – Machine learning
• beautifulsoup4 – Web scraping
• pillow – Image processing
• sqlalchemy – Database ORM

Example Projects

Web Scraper

pip3 install requests beautifulsoup4

import requests
from bs4 import BeautifulSoup

url = "https://example.com"
response = requests.get(url)
soup = BeautifulSoup(response.text, 'html.parser')
print(soup.title.text)

Simple HTTP Server

python3 -m http.server 8000

Access at: http://localhost:8000

Troubleshooting

pip: command not found

Use pip3 instead:

python3 -m pip install requests

Permission Denied Error

Don’t use sudo with pip. Use –user flag:

pip3 install --user requests

Old Python 2 Available

Python 2 is deprecated. Install Python 3:

sudo apt install python3 python3-pip

Conclusion

You now have Python installed and ready to use on Debian! Key commands to remember:

• python3 – Start Python interpreter
• pip3 install package – Install packages
• python3 -m venv – Create virtual environment
• pip3 list – List installed packages